SAINT-MANDÉ, France — For all her 30 years, Jennifer Sebag has lived in a community that embodies everything modern Europe is supposed to be. Inclusive, integrated, peaceful and prosperous, the elegant city of Saint-Mandé — hard against Paris’s eastern fringe — has been a haven for Jews like Sebag whose parents and grandparents were driven from their native North Africa decades ago by anti-Semitism. “I’ve always told everyone that here, we are very protected. It’s like a small village,” Sebag said. But in an instant on the afternoon of Jan. 9, Sebag’s refuge became a target. A gunman who would later say he was acting on behalf of the Islamic State walked into her neighborhood’s kosher market and opened fire, launching a siege that would leave four hostages dead — all of them Jewish.

